Route Maps 385 where routemail is an arbitrary name chosen for the route map, 10 is the route map sequence number, and the sequence number is 10 by default, unless another number is specified. We will now set the criteria for the first match clause: match ip address 101 where 101 is the access list that the match clause is checking traffic against. We will now use the set clause to specify the next-hop address of traffic satisfying the match clause: set ip next-hop 172.16.2.2 where 172.16.2.2 is the IP address of the next-hop router. Finally, we need to specify where to send traffic if the match condition is not met: route-map routemail permit 20 set ip next-hop 172.16.1.2 where 20 is the sequence number and 172.16.1.2 is the next-hop router. RouterA will now send all SMTP traffic over the 56Kbps link to RouterC and all other traffic over the 1.544Mbps link to RouterB, as shown in Figure 10.13. FIGURE 10.13 Policy routing configuration for example 1 Internet access-list 101 permit tcp any any eq 25 ! route-map routemail permit 10 match ip address 101 set ip next-hop 172.16.2.2 ! route-map routemail permit 20 set ip next-hop 172.16.1.2 172.16.2.2/24 172.16.1.2/24 56Kbps link SMTP WWW, FTP, etc. 1.544Mbps link 172.16.1.1/24 172.16.2.1/24 s1 s0 ISP A RouterB ISP B RouterC Company A RouterA Copyright ©2001 SYBEX , Inc., Alameda, CA www.sybex.com 386 Chapter 10  Route Optimization Policy Routing Subnets As another example, consider the following scenario. Company A has the same ISP connections as in the previous example. Inside Company A, we have two VLANs, the Engineering VLAN (172.16.3.0/24) and the Account- ing VLAN (172.16.4.0/24), as illustrated in Figure 10.14. Our goal is to direct traffic from the Engineering VLAN (172.16.3.0/24) out the 1.544Mbps link (interface s0) and to direct traffic from the Accounting VLAN (172.16.4.0/24) out the 56Kbps link (interface s1). FIGURE 10.14 Policy routing example 2 First, we need to create our access lists, specifying the conditions we’re looking for, that is, whether a packet was sourced from the Engineering or Accounting VLAN: access-list 1 permit 172.16.3.0 0.0.0.255 access-list 2 permit 172.16.4.0 0.0.0.255 Next, we need to create our route map and specify the match and set parameters. In this example, we will use the name “routevlan”: route-map routevlan permit 10 match ip address 1 set interface serial0 ! Internet 172.16.2.2/24 172.16.1.2/24 56Kbps link 1.544Mbps link 172.16.1.1/24 172.16.2.1/24 172.16.3.1/24 172.16.4.1/24 s1 s0 e1 e0 ISP A RouterB ISP B RouterC RouterA Company A Engineering VLAN Accounting VLAN Copyright ©2001 SYBEX , Inc., Alameda, CA www.sybex.com Route Maps 387 route-map routevlan permit 20 match ip address 2 set interface serial1 The Accounting users will now have their Internet traffic directed to ISP B, while the Engineering users will have their Internet traffic directed to ISP A, as shown in Figure 10.15. FIGURE 10.15 Policy routing configuration for example 2 Internet access-list 1 permit 172.16.3.0 0.0.0.255 access-list 2 permit 172.16.4.0 0.0.0.255 ! route-map routevlan permit 10 match ip address 1 set interface serial0 ! route-map routevlan permit 20 match ip address 2 set interface serial1 172.16.2.2/24 172.16.1.2/24 56Kbps link 1.544Mbps link 172.16.1.1/24 172.16.2.1/24 172.16.3.1/24 172.16.4.1/24 s1 s0 e1 e0 ISP A RouterB ISP B RouterC RouterA Company A Engineering VLAN Accounting VLAN Copyright ©2001 SYBEX , Inc., Alameda, CA www.sybex.com 388 Chapter 10  Route Optimization Summary In this chapter, we discussed how to take networks running different routing protocols and allow them to exchange routing information, through a process called route redistribution. One of the challenges of route redistri- bution is that many routing protocols use different metrics. To overcome this challenge, we set default metrics for various routing protocols. After exam- ining several redistribution examples, we reviewed commands for verifying and troubleshooting route redistribution. We explored various advanced route-manipulation techniques including setting metrics on a protocol-by-protocol basis and setting metrics for spe- cific routes. We introduced the distribute-list feature as a tool for fil- tering the receiving or advertising of routes, and we showed the virtual interface Null0 to be an efficient way of discarding packets destined for spec- ified networks. We also detailed how to redistribute static and connected routes. Finally, we introduced the powerful features of route maps. We used the route map components, match and set clauses, in examples where we routed traffic based on the source network and Layer 4 information (TCP port numbers). Key Terms Before taking the exam, make sure you are familiar with the following terms: hop count metric Null0 route redistribution Copyright ©2001 SYBEX , Inc., Alameda, CA www.sybex.com Written Lab 389 Written Lab Write the configuration for the RouterA, such that HTTP traffic is directed to RouterC, and all other traffic is directed to RouterB, as shown in the following graphic: Solution The first step is to create an access list that specifies the traffic we are inter- ested in, which in this case is HTTP traffic. By default, HTTP uses TCP port 80. Therefore, our access list would be access-list 101 permit tcp any any eq 80 Next, we need to create a route map. In this exercise, we will name it “routeweb”: route-map routeweb permit 10 We’ll now set the criteria for the first match clause: match ip address 101 Next, we will use the set clause to specify the next-hop address of traffic satisfying the match clause: set ip next-hop 172.16.1.1 Internet 172.16.1.1 172.16.2.1 T3 T1 RouterB RouterC RouterA HTTP Telnet, FTP, etc. Copyright ©2001 SYBEX , Inc., Alameda, CA www.sybex.com 390 Chapter 10  Route Optimization Finally, we need to specify where to send traffic if the match condition is not met: route-map routeweb permit 20 set ip next-hop 172.16.2.1 RouterA will now send all HTTP traffic over the T3 link to RouterC and all other traffic over the T1 link to RouterB. Hands-on Lab Add a distribute-list command to RouterA, such that RouterB can see network 1.1.1.0/24 in its routing table, but not network 2.2.2.0/24, as shown in the following graphic: Solution RouterA and RouterB should have their s0 interfaces interconnected with a serial crossover cable. We will arbitrarily designate RouterB as the DCE side and RouterA as the DTE side. First, we create an access list on RouterA that specifies which networks we want to be advertised: access-list 1 permit 1.0.0.0 0.255.255.255 Next, we use the distribute-list command to permit only the net- work specified in the access list: router rip distribute–list 1 out Lo0 1.1.1.1/24 RouterA RouterBRIP s0 s0 Lo1 2.2.2.2/24 3.3.3.1/24 3.3.3.2/24 Copyright ©2001 SYBEX , Inc., Alameda, CA www.sybex.com Hands-on Lab 391 Following are possible configurations for RouterA and RouterB: RouterA ! version 11.2 ! hostname RouterA ! interface Loopback0 ip address 1.1.1.1 255.255.255.0 ! interface Loopback1 ip address 2.2.2.2 255.255.255.0 ! interface Serial0 ip address 3.3.3.1 255.255.255.0 ! router rip distribute-list 1 out network 1.0.0.0 network 2.0.0.0 network 3.0.0.0 ! access-list 1 permit 1.0.0.0 0.255.255.255 ! no ip classless ! line con 0 line aux 0 line vtp 0 4 login ! end Copyright ©2001 SYBEX , Inc., Alameda, CA www.sybex.com 392 Chapter 10  Route Optimization RouterB ! version 11.2 ! hostname RouterB ! interface Serial0 ip address 3.3.3.1 255.255.255.0 clockrate 56000 ! router rip network 3.0.0.0 ! no ip classless ! line con 0 line aux 0 line vtp 0 4 login ! end Issuing the show ip route command on RouterB reveals that RouterB has entries for networks 1.1.1.0 and 3.3.3.0 but not for network 2.2.2.0. Copyright ©2001 SYBEX , Inc., Alameda, CA www.sybex.com Review Questions 393 Review Questions 1. Which of the following is the metric used by RIP? A. Ticks B. Bandwidth C. Delay D. Hop count 2. Which of the following is the network address and subnet mask of the default route? A. 127.0.0.1 255.255.255.255 B. 0.0.0.0 0.0.0.0 C. 255.255.255.255 0.0.0.0 D. 255.255.255.255 255.255.255.255 3. What are the two clauses used by route maps? A. metric B. match C. access D. set 4. Which of the following are Cisco proprietary protocols? (Choose all that apply.) A. RIP B. IGRP C. OSPF D. EIGRP Copyright ©2001 SYBEX , Inc., Alameda, CA www.sybex.com 394 Chapter 10  Route Optimization 5. Which of the following are metric components of IGRP? (Choose all that apply.) A. Delay B. Hops C. Bandwidth D. Ticks 6. What number would we assign to the load component of an EIGRP metric to indicate that a link was approximately 10 percent loaded? A. 10 B. 1 C. 2.5 D. 25 7. What is the default MTU size metric component for an Ethernet interface? A. 1500 bytes B. 1518 bytes C. 64 bytes D. 4000 bytes 8. What is the most desirable value for the reliability metric component? A. 255 B. 0 C. 1 D. 100 Copyright ©2001 SYBEX , Inc., Alameda, CA www.sybex.com [...]... auto-summary C no summary stub D no route-summary 19 Which is true regarding routing protocols? A Classless routing protocols send periodic subnet mask information B Classless routing protocols send incremental subnet mask information C Classless routing protocols send prefix mask information D All devices on a network running classless routing protocols must use the same mask 20 Which of the following commands... ping an unnumbered interface 28 Which of the following is true regarding routing protocols? A Classful routing protocols send periodic subnet mask information B Classful routing protocols send incremental subnet mask information C Classful routing protocols send prefix mask information D All devices on a network running classful routing protocols must use the same mask 29 In the IOS command used to create... routes permanent B It takes manually configured routes and redistributes them into a specified routing protocol C It takes routes from directly connected interfaces and redistributes them into a specified routing protocol D It causes the same metric to be used for a routing protocol, regard- less of which routing protocol it is being redistributed into 11 Which syntax used with the clear ip bgp command... Which of the following commands will redistribute manually config- ured routes into a specified routing process? A redistribute connected B redistribute static C redistribute default D redistribute local 15 If a local interface is not part of a routing process, what command may be used to inject its route into a routing process? A redistribute connected B redistribute static C redistribute default D redistribute... 0 is said to be a back- bone router C If an IGRP routing process connects to a multi-area OSPF net- work, the router through which it enters the OSPF network is called an ABR D An ASBR separates two or more OSPF areas 16 If you wanted to reduce bandwidth usage, which Cisco IOS features could you use? (Choose all that apply.) A Access lists B Snapshot routing C Compression of WANs D TTL E DDR F Incremental... destination network 2 B Cisco uses 0.0.0.0 0.0.0.0 to indicate a default route in a static routing statement 3 B and D Route maps have two primary components, a match clause and a set clause The function of the match clause is to specify the traffic that is to be policy routed The purpose of the set clause is to manipulate the routing of traffic by adjusting such parameters as nexthop address 4 B and D IGRP... prevents or permits the routes specified in access-list 2 from being added to the local routing table B It prevents or permits the routes specified in access-list 2 from being advertised C It redirects the routes specified in access-list 2 to the Null0 interface D It redistributes routes specified in access-list 2 to all routing protocols Copyright ©2001 SYBEX , Inc., Alameda, CA www.sybex.com 398 Chapter... Appendix A Practice Exam 31 If you wanted to provide stability and availability, which Cisco IOS features could you use? (Choose all that apply.) A Reachability B Convergence C Alternative path routing D Snapshot routing E Tunneling F Dial backup G Load balancing 32 Which of the following is a disadvantage to segmenting a network with bridges? A Bridges do not segment the network B Bridges only create... across multiple EIGRP processes? (Choose all that apply.) A Non-optimal route choices B Slow convergence C Routing loops D Broadcast storms 37 If you want to allow routes to enter a route interface, but deny any route information from exiting the specified interface, which IOS command must you use? A no routing B access filters C access lists D passive interface 38 In the IOS command match ip address 1,... excessively 4 B EIGRP relies on multicasts to send queries and updates to other EIGRP peers 5 A The IOS command clear ip route * will clear dynamically established routes from a router’s routing table When troubleshooting routing problems, this command can be useful in clearing route tables immediately, instead of waiting for convergence processes to complete The other options are invalid syntax 6 A, B . different routing protocols and allow them to exchange routing information, through a process called route redistribution. One of the challenges of route redistri- bution is that many routing. specified routing protocol. C. It takes routes from directly connected interfaces and redistributes them into a specified routing protocol. D. It causes the same metric to be used for a routing. routes into a specified routing process? A. redistribute connected B. redistribute static C. redistribute default D. redistribute local 15. If a local interface is not part of a routing process, what